The more I work in this field, the more I think that this is the best and quickest way to build good software.
Once you realize that everything you write is disposable, you have freed yourself to just write and judge later.
It's not how fast you get started, it's how fast you finish. Sometimes the long roads around is quicker.
Focused, hard work is the real key to success. Keep your eyes on the goal, and just keep taking the next step towards completing it. If you aren't sure which way to do something, do it both ways and see which works better.
The best way to build the best X, is to build 5 of them.. by the 5th you're pretty awesome at building X. Seems like too many people believe instead, in meticulous up front design analysis etc etc.
The other point is that in my experience, the rewrites take less and less time to write, as you know more and more.